> Could you provide a testcase and name UAs that fail it to show the problem
> you say exists?
[the problem of not all Unicode characters being displayed]
This is a good test case:
http://www.petesguide.com/WebStandards/tests/TypesettingCharsFontTest.html
It shows many Unicode typographic characters that are not commonly
supported--including character such as "SM", "black diamond suit", and most of
the typographic spaces.